Solvent extraction of silver(I) as anionic metal complexes with 2-thenoyltrifluoroacetone and 4-isopropyltropolone into chloroform in the presence of tetrabutylammonium ions

The solvent extraction of silver(I) in aqueous 0.1 mol dm(-3) sodium nitrate solutions with 2-thenoyltrifluoroacetone (Htta) and 4-isopropyltropolone (beta-isopropyltropolone, Hipt) into chloroform was studied in the absence and presence of tetrabutylammonium ions (tba(+)), and the results were compared. Although extraction with Htta was poor, it was very much enhanced and nearly quantitative extraction was achieved by the addition of tba(+). This was assumed to be due to the fact that the complex, Ag(tta), was hydrophilic due to its hydration, but tba(+)Ag(tta)(2)(-), which was extracted in the presence of tba(+), was very weakly hydrated and bulkier. Both Ag(ipt) and Ag(ipt)(Hipt) were extracted; extraction with Hipt was not very effective in the absence of tba(+). By the addition of tba(+), the anionic complex, tba(+)Ag(ipt)(2)(-), was also extracted, and nearly quantitative extraction was also achieved. Since the formation of this anionic complex is made by an exchange of ipt(-) with Hipt of the Ag(ipt)(Hipt) species, the enhancement of extraction was impaired by the dissociation of Hipt from the self-adduct.